CE 478
Microcontroller Systems
Spring 2011
Prof. Dan Ernst
http://www.cs.uwec.edu/~ernstdj/courses/ce478
CS 478: Microcontroller Systems
University of Wisconsin-Eau Claire
Dan Ernst
Welcome
• Class overview
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Policies etc.
What are embedded systems?
Why are they interesting?
Why are they needed?
• Note: There is no required textbook for this class!
Office hours:
Wednesday: 9 – 11 am
Friday: 1 – 3 pm
or by appointment
CS 478: Microcontroller Systems
University of Wisconsin-Eau Claire
Dan Ernst
Labs and Equipment
• Fridays are Lab days in P 122. (not 171!)
– There may be some exceptions (watch your e-mail!)
• In labs you will sometimes be in groups of 2
• Equipment needs to stay in the lab area.
CS 478: Microcontroller Systems
University of Wisconsin-Eau Claire
Dan Ernst
Grading*
Item
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Labs/Homeworks
Exams (2)
Project
Quizzes
CS 478: Microcontroller Systems
University of Wisconsin-Eau Claire
Weight
=========
30%
30% (15% midterm; 15% final)
30%
10%
Dan Ernst
Final Project
• Final Project will involve constructing a “polished” digital system
– Implement the hardware and software involved in your design
– Ideas and examples of projects are/will be posted on the class website
• Project will involve multiple phases
– Proposal
– Implementation
– Presentation/Documentation
CS 478: Microcontroller Systems
University of Wisconsin-Eau Claire
Dan Ernst
What we will cover*
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PowerPC architecture and assembly language
Bus protocols and interfacing
– Including P6, PPC, and maybe others
Digital design review
Common I/O devices
– Timers, A/D converters, serial I/O, etc.
Interrupts
– I/O devices demanding attention
Direct Memory Access (DMA):
– I/O devices talk directly to memory
Memory technologies: SRAM, DRAM, Flash etc
Analog to digital and back again.
Error correction and other “special” topics.
CS 478: Microcontroller Systems
University of Wisconsin-Eau Claire
Dan Ernst
Administrivia
P122 access:
You’re welcome to work in P122 on 478-related projects anytime,
except Weds. 2 – 4 pm and Tues. 3:30 – 5:30 pm ( CS 278 lab)
If you can avoid it, don’t leave the boards out – there will be plenty of
cabinet space, and other classes (CS 278) need to use the space. You
will receive a key to the cabinets on the first lab day.
Please don’t distribute the access code, or let in extra people!
http://www.cs.uwec.edu/comdistro
CS 478: Microcontroller Systems
University of Wisconsin-Eau Claire
Dan Ernst
CS 478: Microcontroller Systems
University of Wisconsin-Eau Claire
Dan Ernst
General Purpose Computers
• Microcomputers are computers based on microprocessors
– General purpose microcomputers
• PC’s, Macs, etc.
– Generally require a large amount of
support circuitry
• Memory, communications, I/O, keyboard,display...
CS 478: Microcontroller Systems
University of Wisconsin-Eau Claire
Dan Ernst
Inside a General Purpose Computer
Address Bus
Data Bus
Control Bus
CPU
PCI
Bus
Bridge
ROM
RAM
Clock,
Reset
circuitry
PCI Bus
Disk
Controller
Video
Memory
Parallel
Interface
Serial
Interface
Real-time
Clock
Keyboard/
Mouse
Controller
...
Disk
Interface
Video
Display
Controller
CS 478: Microcontroller Systems
University of Wisconsin-Eau Claire
Dan Ernst
Does One Size Fit All?
• Advantages of a general-purpose computer
– Flexible - can run lots of programs and interface with lots of devices
– Expandable - can be updated with new hardware
– Cost-effective - the cost of adding a new program is small
– Economy of scale - millions are being produced…
• Disadvantages
– Must be a “super” system, capable of running any program
– High price
– Relatively large, short battery life
CS 478: Microcontroller Systems
University of Wisconsin-Eau Claire
Dan Ernst
Embedded Systems
• Embedded Systems are small, special-purpose computer systems
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Rocket guidance systems
Toaster control systems
Handheld electronics
Toys
– Only the necessary parts are included
• Cheaper, smaller
– Simpler --> more reliable?
CS 478: Microcontroller Systems
University of Wisconsin-Eau Claire
Dan Ernst
Needs of Typical Embedded Systems
• Consider the following embedded systems:
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Programmable thermostat
Blood Glucose Meter
iPod Touch™
Automobile System Controller
• Single-purpose
• Small
• Inexpensive
• Reduced computation needs (most of the time)
• Special interfaces
• Lightweight (often hand held)
CS 478: Microcontroller Systems
University of Wisconsin-Eau Claire
Dan Ernst
So…
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You don't need a traditional user interface to decide which programs should be
running
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You don't need to dynamically load programs into your devices
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You don't need to waste time waiting for the O/S to load
– if one is needed, then it doesn't have baggage that make it slow to load
•
You don't need to load programs or data from a slow disk drive - most
information needed will be in fast ROM
CS 478: Microcontroller Systems
University of Wisconsin-Eau Claire
Dan Ernst
Why PCs Aren’t Practical for Everything
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What does it take to build a blood glucose meter using a typical PC
microprocessor?
• 1 Intel/AMD/other CPU
• Dynamic RAM, controller
• ROM (one or two chips) for program
• Real-time clock
• LCD panel
• Serial interface ports, drivers
• A/D Converter
• Random support chips (five or six chips)
• This is going to take around 5+ chips, use > 100 W, and cost > $400.
CS 478: Microcontroller Systems
University of Wisconsin-Eau Claire
Dan Ernst
ASICs: The Other End of the Spectrum
• Since consumer electronics are made to do one thing, we should just
be able to hardwire a solution!
• Construct an ASIC (Application-Specific Integrated Circuit)
– Custom chip that does a single thing, but does it VERY well!
– Very little need for software support
• Downside: making a custom mask will cost you a fortune
– Lots of engineering design time
– At least $10,000 up front to make a mask
– $$$ to reserve time in the fab (or build your own fab)
CS 478: Microcontroller Systems
University of Wisconsin-Eau Claire
Dan Ernst
FPGA – a middle solution?
• Could use an Field-Programmable Gate Array (FPGA)
– (a la 278)
• Advantages:
– Programmable
– Much cheaper than ASICs
• (at least in small quantities)
• Disadvantages:
– Not as intuitive as software
– Still not super-cheap
– Take up a lot of space/power relative to the capability they bring
CS 478: Microcontroller Systems
University of Wisconsin-Eau Claire
Dan Ernst
The Spectrum of Hardware/Software Solutions
CS 478: Microcontroller Systems
University of Wisconsin-Eau Claire
Dan Ernst
Why Consumer Electronics make Money
• A Microcontroller is a small CPU with support devices built into the chip
– Small CPU
– Small ROM
– RAM, EEPROM
– Parallel ports
– RS232 ports
– A/D Converter
– Timer
• Typically, a microcontroller uses little power and costs $0.50 to $100.00
CS 478: Microcontroller Systems
University of Wisconsin-Eau Claire
Dan Ernst
A Generic Microcontroller
Flash
EEROM
2KB – 256KB
Timer
16-32 Bit
RAM
256B – 64KB
Small CPU Core
8-32 Bits
2-40 MHz
RS232/
USB
I2C/SPI
CS 478: Microcontroller Systems
University of Wisconsin-Eau Claire
ADC
8-14 Bits
GPIO
Memory Bus
16-24 Bits
Dan Ernst
Embedded Systems
Definition:
• Dedicated to controlling a specific real-time device or function
• Self-starting, not requiring human intervention to begin. The user
cannot tell if the system is controlled by a microprocessor or by
dedicated hardware (or magic!)
• Self-contained, with the operating program in some kind of non-volatile
memory
CS 478: Microcontroller Systems
University of Wisconsin-Eau Claire
Dan Ernst
How are things controlled?
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Switches
– Switches can be used to switch things on or off e.g. lights can be on or off
– They can also be used to switch between values e.g a heater can be set
to a number of values
Sensors
– Sensors can tell if something is on or off
– Sensors can tell you the value of something e.g. temperature
Timers
– Timers can control the duration of other activities, such as how long a light
is on, or the time between ADC samples
Analog controllers
– Things such as voltage can be set for analog devices such as motors
CS 478: Microcontroller Systems
University of Wisconsin-Eau Claire
Dan Ernst
What we will cover*
•
•
•
•
•
•
•
•
•
PowerPC architecture and assembly language
Bus protocols and interfacing
– Including P6, PPC, and maybe others
Digital design review
Common I/O devices
– Timers, A/D converters, serial I/O, etc.
Interrupts
– I/O devices demanding attention
Direct Memory Access (DMA):
– I/O devices talk directly to memory
Memory technologies: SRAM, DRAM, Flash, etc.
Analog to digital and back again.
Error correction or other “special” topics
CS 478: Microcontroller Systems
University of Wisconsin-Eau Claire
Dan Ernst